Cultivation of Aerobic Granular Sludge with Magnetic Seed and Its Effect on Membrane Fouling in MBR

Aerobic granular sludge with magnetic seed was cultivated in MBR to treat artificially synthetic wastewater,and its effect on membrane fouling was investigated.The results indicate that during the process of cultivating aerobic granular sludge with magnetic seed by flocculent activated sludge,at the beginning,a considerable amount of filamentous bacteria is propagated,then the filamentous bacteria aggregate into very small granules,at last,the matured granular sludge is gradually formed with smooth surface and approximately spherical or spheroidal shape.The size of matured aerobic granular sludge with magnetic seed is 0.47 to 4.1 mm,and the average value is 1.7 mm.The SVI value is less than 70 mL/g,which is far less than that of conventional activated sludge(100 to 150 mL/g).The settling velocity is increased with the increase of granule size,with a range of 30 to 91 m/h,which is far more than that of conventional activated sludge(8 to 10 m/h).The variation trend of membrane fluxes in MBRs filled with flocculent activated sludge and aerobic granular sludge with magnetic seed indicates that the decline rate of membrane flux in MBR filled with aerobic granular sludge with magnetic seed is less than that in MBR filled with conventional activated sludge,this results from the combined action of aerobic granular sludge with magnetic seed and the flow state of the reactor.